HD 114762 b

Not to be confused with HD 114762 b's stellar companion, HD 114762.

HD 114762 b is a small red dwarf star, in the HD 114762 system,^[3] formerly thought to be a massive gaseous^[6][7] extrasolar planet,^[8] approximately 126 light-years (38.6 pc) away in the constellation of Coma Berenices.^[1][6] This optically undetected companion to the late F-type main-sequence star HD 114762 was discovered in 1989 by Latham, et al.,^[7] and confirmed in an October 1991 paper by Cochran, et al.^[9] It was thought to be the first discovered exoplanet (although its existence was confirmed after those around PSR B1257+12.)

HD 114762 b^[1]

Observation data Epoch J2000      Equinox J2000
Constellation	Coma Berenices
Right ascension	13h 12m 19.7428s[2]
Declination	+17° 31′ 01.654″[2]
Astrometry
Distance	126±2[2] ly (38.6±0.7[2] pc)
Orbit
Primary	HD 114762
Period (P)	83.915±0.003 d[3]
Semi-major axis (a)	0.375±0.006 AU[3]
Eccentricity (e)	0.566+0.012 −0.011[3]
Inclination (i)	6.23+1.97 −1.26[3]°
Periastron epoch (T)	2449889.106±0.186[4]
Argument of periastron (ω) (secondary)	201.3±1.0[3]°
Semi-amplitude (K2) (secondary)	612.48±3.52[4] km/s
Details
Mass	107+20 −27[3] 147.0+39.3 −42.0[5] MJup
Database references
SIMBAD	data

The object orbits the primary star every 83.9 days at an approximate distance of 0.37 AU,^[3] with an orbital eccentricity of 0.57;^[3] for comparison, this orbit is similar to that of Mercury but with almost three times the eccentricity.^[3] Based on the radial velocity measurements alone, it was estimated to have a minimum mass of 11.069±0.063  M_J (at 90°)^[10] and a probable mass of approximately 63.2 M_J (at 10°).^[11] However, analysis of its astrometric perturbation of its host star in 2019 found it to have an extremely low inclination of only 6.23+1.97
−1.26 degrees, giving it a true mass of 107+20
−27 M_J and putting it well outside of the range of planetary masses (less than 13 M_J).^[3]

HD 114762 b was thought for a time to be the first extrasolar planet ever detected, predating the 1992 pulsar planets found around PSR B1257+12 and main-sequence yellow dwarf 51 Pegasi.^[12][13] However, now that it has been found to not be a planet, the planets found orbiting PSR B1257+12 were indeed the first exoplanets ever found.^[3]

At an event celebrating the career of discoverer David Latham and attended by his colleagues and collaborators, the object was informally dubbed "Latham's Planet".^[14] However, this name has no official standing with the International Astronomical Union.

See also

• 51 Pegasi b
• Gamma Cephei Ab

References

1. Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701. S2CID 119067572.
2. Brown, A. G. A; et al. (2016). "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties". Astronomy and Astrophysics. 595. A2. arXiv:1609.04172. Bibcode:2016A&A...595A...2G. doi:10.1051/0004-6361/201629512. S2CID 1828208.Gaia Data Release 1 catalog entry
3. Kiefer, Flavien (17 October 2019). "Determining the mass of the planetary candidate HD 114762 b using Gaia". Astronomy & Astrophysics. 632: L9. arXiv:1910.07835. Bibcode:2019A&A...632L...9K. doi:10.1051/0004-6361/201936942. S2CID 204743831.
4. Kane, Stephen R.; et al. (2011). "Revised Orbit and Transit Exclusion for HD 114762b". The Astrophysical Journal Letters. 735 (2). L41. arXiv:1106.1434. Bibcode:2011ApJ...735L..41K. doi:10.1088/2041-8205/735/2/L41. S2CID 118409104.
5. Kiefer, F.; et al. (January 2021). "Determining the true mass of radial-velocity exoplanets with Gaia. Nine planet candidates in the brown dwarf or stellar regime and 27 confirmed planets". Astronomy & Astrophysics. 645 A7. arXiv:2009.14164. Bibcode:2021A&A...645A...7K. doi:10.1051/0004-6361/202039168. S2CID 221995447.
6. North, Gerald (2003). Astronomy in Depth. New York: Springer. p. 185. ISBN 9781852335809.
7. Latham, David W.; et al. (4 May 1989). "The unseen companion of HD114762: a probable brown dwarf". Nature. 339 (6219): 38–40. Bibcode:1989Natur.339...38L. doi:10.1038/339038a0. S2CID 4324036.
8. "HD 114762b". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 31 August 2014.
9. Cochran, William D.; et al. (10 October 1991). "Constraints on the Companion Object to HD 114762". The Astrophysical Journal. 380: L35–L38. Bibcode:1991ApJ...380L..35C. doi:10.1086/186167.
10. Wang, Sharon Xuesong; et al. (2012). "The Discovery of HD 37605c and a Dispositive Null Detection of Transits of HD 37605b". The Astrophysical Journal. 761 (1): 46–59. arXiv:1210.6985. Bibcode:2012ApJ...761...46W. doi:10.1088/0004-637X/761/1/46. S2CID 118679173.
11. Kane, Stephen R. & Gelino, Dawn M. (2012). "Distinguishing between stellar and planetary companions with phase monitoring". Monthly Notices of the Royal Astronomical Society. 424 (1): 779–788. arXiv:1205.5812. Bibcode:2012MNRAS.424..779K. doi:10.1111/j.1365-2966.2012.21265.x. S2CID 15537565.
12. Hale, Alan (1995). "On the Nature of the Companion to HD 114762". Publications of the Astronomical Society of the Pacific. 107 (707). The University of Chicago Press: 22–26. Bibcode:1995PASP..107...22H. doi:10.1086/133511. JSTOR 40680489.
13. Marcy, Geoffrey W.; et al. (1999). "Two New Candidate Planets in Eccentric Orbits". The Astrophysical Journal. 520 (1): 239–247. arXiv:astro-ph/9904275. Bibcode:1999ApJ...520..239M. doi:10.1086/307451. S2CID 16827678.
14. Johnson, John (2016). How do you find an Exoplanet?. New Jersey: Princeton University Press. p. 137. ISBN 978-0-691-15681-1.